U.S. patent number 5,221,170 [Application Number 07/716,761] was granted by the patent office on 1993-06-22 for coated threaded fasteners.
This patent grant is currently assigned to Nylok Fastener Corporation. Invention is credited to Max F. Dorflinger, Joseph R. Dudley, Richard J. Duffy, Gregory A. Fruehe.
United States Patent |
5,221,170 |
Duffy , et al. |
June 22, 1993 |
**Please see images for:
( Reexamination Certificate ) ** |
Coated threaded fasteners
Abstract
This invention relates to threaded fasteners, an apparatus for
making such threaded fasteners and methods of fastening parts. The
tip of the shank of a threaded fastener has at least one thread
coated with a lubricating or masking material to reduce the drive
torque necessary for fastening as well as provide a protective
coating for the fastener during subsequent processing operations.
The drill tip of the disclosed self-drilling fasteners is coated
with a lubricating material to reduce drive torque and to eliminate
binding when drilling through fibrous material. The present
invention also prevents the build-up of corrosion inhibiting
materials on threaded fasteners attached to parts to be fastened
together. A masking and/or insulating material is first applied to
the threaded fasteners attached to the parts to substantially
prevent applied corrosion inhibitor from adhering to the threads of
the fastener. A method of fastening parts, including fibrous
material such as carpet or sound insulation, is also accomplished
through practice of the present invention. The apparatus of the
present invention provides a resin type stream entrained in a
gaseous jet directed through a nozzle onto the threads of a
fastener. The apparatus provides selectable thread coverage,
including complete coverage of all threads.
Inventors: |
Duffy; Richard J. (Utica,
MI), Dudley; Joseph R. (Southfield, MI), Fruehe; Gregory
A. (Kalamazoo, MI), Dorflinger; Max F. (Washington,
MI) |
Assignee: |
Nylok Fastener Corporation
(Rochester, MI)
|
Family
ID: |
27403247 |
Appl.
No.: |
07/716,761 |
Filed: |
June 18, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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281633 |
Dec 9, 1988 |
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907582 |
Sep 15, 1986 |
4775555 |
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913339 |
Sep 30, 1986 |
4835819 |
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Current U.S.
Class: |
411/428;
411/387.1; 411/411; 411/903; 411/914; 470/2 |
Current CPC
Class: |
B05B
13/06 (20130101); B05B 13/0654 (20130101); B05D
7/22 (20130101); F16B 33/06 (20130101); B05D
1/02 (20130101); B05D 3/0218 (20130101); B05D
2258/02 (20130101); B05D 2401/32 (20130101); B05D
2506/15 (20130101); F16B 39/225 (20130101); F16B
39/34 (20130101); Y10S 411/914 (20130101); Y10S
411/903 (20130101) |
Current International
Class: |
B05D
7/22 (20060101); B05D 7/22 (20060101); B05B
13/06 (20060101); B05B 13/06 (20060101); F16B
33/00 (20060101); F16B 33/00 (20060101); F16B
33/06 (20060101); F16B 33/06 (20060101); B05D
3/02 (20060101); B05D 3/02 (20060101); B05D
1/02 (20060101); B05D 1/02 (20060101); F16B
39/00 (20060101); F16B 39/00 (20060101); F16B
39/34 (20060101); F16B 39/34 (20060101); F16B
39/22 (20060101); F16B 39/22 (20060101); F16B
025/00 (); F16B 037/00 (); B21D 053/20 () |
Field of
Search: |
;411/411,424,428,287,258,386,387,900-903,908,914
;10/1R,1P,86A,86R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2733802 |
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Feb 1979 |
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DE |
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119210 |
|
Sep 1980 |
|
JP |
|
Primary Examiner: Wilson; Neill R.
Attorney, Agent or Firm: Niro, Scavone, Haller &
Niro
Parent Case Text
This application is a continuation of U.S. application Ser. No.
281,633, filed Dec. 9, 1988, now abandoned, which is a continuation
in part of U.S. application Ser. No. 907,582, filed Sep. 15, 1986,
now U.S. Pat. No. 4,775,555, and U.S. application Ser. No. 913,339,
filed Sep. 30, 1986, now U.S. Pat. No. 4,835,819.
Claims
What is claimed is:
1. A threaded article having a coating on its thread,
comprising:
a fastener having a threaded portion adapted for uniform engagement
with a mating fastener;
a masking and insulating coating deposited on said fastener to form
a substantially uniform layer covering at least a part of said
threaded portion enabling the mating fastener to couple with said
threaded article;
said fastener being heated, prior to the deposition of said
coating, to a temperature sufficient to enable said coating to
adhere to said threaded portion; and
said threaded article being capable of exhibiting substantially
uniform torque-tension curve behavior during engagement with said
mating fastener, and said coating being substantially resistant to
the deposition of corrosion resistant materials.
2. The threaded article of claim 1 wherein said masking and
insulating coating is a masking, insulating and lubricating
coating.
3. The threaded article of claim 1 wherein said masking and
insulating coating comprises a fluorocarbon type coating.
4. The threaded article of claim 1 wherein said masking and
insulating coating comprises a Teflon type coating.
5. The threaded article of claim 1 wherein said masking and
insulating coating is at least about 20 microns to about 50 microns
thick.
6. The threaded article of claim 1 wherein said threaded article
comprises a nut.
7. The threaded article of claim 1 wherein said masking and
insulating coating comprises a Teflon-P powder type coating.
8. The threaded article of claim 1 wherein said masking and
insulating coating provides an insulating barrier for at least two
seconds at about 500 to about 600 volts electrical potential
applied across said uniform layer.
9. The threaded article of claim 1 wherein said threaded article
comprises a stud.
10. The threaded article of claim 1 wherein said threaded article
comprises an internally threaded well.
11. The threaded article of claim 1 wherein said threaded article
comprises an internally threaded article.
12. The threaded article of claim 1 wherein said threaded article
comprises an externally threaded article.
13. The threaded article of claim 1 wherein said threaded article
comprises a deformed all-metal nut, said deformed all-metal nut
having a top surface at one end defining a circular opening
thereon, a bottom surface at a second end defining a deformed
circular opening thereon, and a continuous thread between said top
and bottom surfaces.
14. A fastener resistant to deposition of corrosion preventative
material comprising:
a threaded portion adapted for uniform engagement with a mating
fastener;
a TEFLON.RTM. powder type coating deposited on said threaded
portion to form a substantially uniform layer providing at least
one of a masking, lubricating and insulating covering on said
threaded portion of said fastener, said fastener being heated to a
temperature sufficient to enable said TEFLON.RTM. type powder to
adhere to said threaded portion, prior to deposition of said
TEFLON.RTM. type coating;
said fastener being capable of exhibiting substantially uniform
torque-tension curve behavior during coupling.
15. The fastener of claim 14 wherein said layer is at least about
20 microns to about 50 microns thick.
16. The fastener of claim 14 wherein said Teflon type coating
consists essentially of Teflon-P material.
17. The fastener of claim 14 wherein said substantially uniform
layer provides a lubricating and at least one of a masking and
insulating covering on said threaded portion of said fastener.
18. A fastener resistant to deposition of corrosion preventative
material comprising:
a threaded portion adapted for engagement with a mating fastener;
and
a TEFLON.RTM. powder type coating deposited on said threaded
portion to form a substantially uniform layer, said uniform layer
providing an insulating barrier for at least two seconds at about
500 to about 600 volts electrical potential applied across said
uniform layer, said fastener being heated to a temperature
sufficient to enable said TEFLON.RTM. type powder to adhere to said
threaded portion, prior to deposition of said Teflon.RTM. type
coating.
19. A threaded fastener comprising:
a heat at one end; and
a threaded shank associated with said head having a coated tip
portion at the other end, at least a portion of said coated tip
being coated with at least one of a lubricating material, an
insulating material and a masking material, said coated tip portion
being capable of reducing and preventing binding when installed
through a fibrous material into an article, said fastener being
heated to a temperature sufficient to enable said at least one of
the lubricating material, insulating material and masking material
to adhere to said portion of said coated tip, prior to deposition
of said at least one of the lubricating material, insulating
material and masking material.
20. The threaded fastener of claim 19 wherein said threaded
fastener is a screw.
21. The threaded fastener of claim 19 wherein said threaded
fastener is a bolt.
22. The threaded fastener of claim 20 wherein said screw is
self-threading.
23. The threaded fastener of claim 19 wherein said fastener
includes means for drilling at said tip portion and is
self-drilling.
24. The threaded fastener of claim 23 wherein said means for
drilling is substantially completely coated with at least one of
said lubricating material, said insulating material and said
masking material.
25. The threaded fastener of claim 23 wherein at least one of said
lubricating material, said insulating material and said masking
material is applied to the drill tip of said screw and to at least
to a portion of one thread of said screw.
26. The threaded fastener of claim 19 wherein at least one thread
is coated substantially 360.degree. about said threaded shank with
at least one of said lubricating material and said masking
material.
27. The threaded fastener of claim 19 wherein said threaded shank
is substantially completely coated with at least one of said
lubricating material and said masking material.
28. A fastening system comprising:
a male segment having a substantially cylindrical threaded
portion;
a female segment having a plurality of threads which interlock with
the threaded portion of said male segment; and
at least one thread of at least one of said male and said female
segment having a coating of at least one of a lubricating material,
insulating material and masking material, said fastening system
being capable of exhibiting substantially uniform torque-tension
curve behavior during coupling, said fastener being heated, prior
to the deposition of said coating, to a temperature sufficient to
enable said coating to adhere to at least one thread of at least
one of said male and said female segment.
29. The fastening system of claim 28 wherein all threads of at
least one of said male segment and said female segment are
substantially completely coated with at least one of said
lubricating material, said insulating material and said masking
material.
30. A threaded fastener comprising:
a top surface at one end defining a circular opening thereon;
a bottom surface at a second end defining a deformed circular
opening thereon; and
a continuous thread between said top and bottom surfaces, at least
a portion of said thread coated with at least one of a masking,
lubricating and insulating material, said fastener being capable of
exhibiting uniform torque-tension curve behavior during coupling,
said fastener being heated, prior to the deposition of said
coating, to a temperature sufficient to enable said coating to
adhere to said portion of said thread.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to improved threaded
elements having a useful coating or patch applied to the threads
which masks, insulates and/or lubricates the threads. More
particularly the invention relates to fastener elements and
apparatus for the processing of such fastener elements wherein a
patch is deposited on the threads ranging from a small patch to
complete coverage of all the threads to mask, insulate and/or
lubricate the threads and a method of using such fasteners.
BACKGROUND OF THE INVENTION
In prior art patents there are disclosed various methods and
apparatus for applying locking patches of resilient resin to
threaded articles. In the devices disclosed in these patents,
generally a rotatable table or transport belts are disposed for
receiving fasteners and transporting them through a plurality of
stations to effect application of the patch to the threads of the
threaded articles or the fastener elements.
U.S. Pat. Nos. 4,054,688 and 4,100,882 are directed to forming
patches on fasteners whereby a portion of the heat fusible resin
particles is deposited on one area of the hot threads of an
element, and thereafter the resin particles are deposited on an
additional area of the threads to produce two distinct patches at a
desired location. In each of the aforementioned patents, internally
threaded articles are retained on a rotatable support member in a
selected position by means of a slot which receives a portion of
the external surface of a hex head nut. After a discrete patch is
applied to the internal threads of the fastener, a turning moment
is applied to the fastener to move it such that a different
external portion of the threads of the hexagonal element is
received by the slot, after which a second discrete patch is
applied to the threads of the fastener.
U.S. Pat. No. 3,858,262 is directed to a method and apparatus for
making a self-locking threaded element which avoids the
difficulties of resin deposit on the end faces of the threaded
element and is effective to deposit resin on the selected threads
with a minimum of spatter on other portions of the threads. In that
method and apparatus as disclosed, a nut or other internally
threaded member is heated. While the nut is mounted with its axis
in an up-and-down position, the internal threads are sprayed with
finely divided resin particles which are caught and built up on the
heated surface to form a plastic body.
U.S. Pat. No. 3,894,509 is directed to an apparatus and method for
mass production of internally threaded elements, including an
automatic means to move a succession of the internally threaded
elements through various stations in which the elements are loaded
onto a conveying and treating member. A resilient resin locking
patch is formed on the threaded surface of the elements by
deposition of heat fusible resin powder and thereafter, the
elements are unloaded.
U.S. Pat. Nos. 3,416,492 and 4,336,190 are directed to methods and
apparatus wherein a self-locking internally threaded element is
manufactured having a locking body of resilient resin provided over
three hundred sixty degrees of arc of a portion of the internal
threads.
Although substantial progress has been achieved in the above
patents, it has become desirable to have an improved coated
threaded article or coated fastener and a method of using the
article which exhibits superior masking, lubricating and/or
insulating characteristics. Furthermore, a superior size, shape and
type of resin deposit or patch application, including the area of
the deposit, shape of the resin spray deposited on the threads and
application of the article in various fastening environments not
previously obtainable by known fasteners or threaded articles is
provided.
By way of example only, in an assembly line for the manufacture of
automobiles, trucks and similar vehicles, line speed and uniformity
are required in fastening parts together. In a vehicle assembly
line, such parts include but are not necessarily limited to door
panels, covering trim, fire walls, rugs, insulation and similar
automotive parts. Traditionally these parts have been assembled by
humans, as well as robots. As the vehicle passes a work station,
parts are supplied to the worker which must be assembled into the
passing vehicle. Typically, the worker assembles these parts with
threaded fasteners and may use an automatic feeding and threading
mechanism to install the fasteners.
In assembling parts, the automobile industry has traditionally
relied on nuts and bolts, self-tapping and self-threading screws,
as well as self-drilling screws. These methods have some inherent
difficulties. For example, problems arise when a threaded fastener,
such as a bolt or nut, is attached to a part prior to passing the
work station. A part may contain a pre-drilled hole or an installed
nut or bolt. When that part is dipped and/or sprayed with a
corrosion inhibiting material, such as Uniprime or other rust
inhibiting coverings, this type of material adheres to one or more
of the threads of the fastener and makes fastening extremely
difficult and time consuming. Another example can be seen in rugs
and sound insulation which have typically been installed with
self-drilling fasteners. The fibrous nature of such material
commonly causes the fastener to bind in the material and/or
increase the drive torque necessary to install the fastener. This
results in slowing of the assembly line and/or sloppy installation
of the parts. Difficulty has also been encountered in installing
self-threading fasteners to attach two parts together. If the holes
are not sized properly and/or substantially aligned, then an
assembly line worker cannot install the fasteners in the allotted
time.
To solve the problem of corrosion inhibitor build-up, the prior art
has focused on applying a removable mask coating, such as a
preformed cap or tape material, to substantially all of the
fastener threads. This has met with only limited success and has
not proven to be as safe and cost effective as desired. In
attempting to solve the problem of reducing installation drive
torque, lubricating coatings such as wax, cadmium wax and the like,
have been used with only limited success and safety. These coatings
have typically been expensive, inconvenient to apply, and at time
have utilized hazardous or toxic materials. Consequently, it has
been necessary to search further for an economical and convenient
way to reduce the drive torque incurred during a fastening
operation, to drill through fibrous materials and to prevent the
unwanted adherence of materials such as rust inhibiting coatings to
at least selected portions of the fasteners.
It is therefore an object of the present invention to provide an
improved coated threaded article or fastener and a method of using
the same having a functional resin type material deposited onto the
threads of the threaded article or fastener.
A further object of the present invention is to provide an improved
coated threaded article and method of using the threaded article
wherein the article has an improved application or deposit of resin
type material which is applied over a desired arcuate and vertical
area of the threads of the article.
A still further object of the invention is to provide a threaded
article and method of use having improved definition of the resin
type material which is applied over a desired arcuate and vertical
area of the threads of the threaded article.
It is also an object of this invention is to provide a coated
threaded article having a coating which protects, insulates or
masks the threads from unwanted contamination or deposition of
material thereon.
SUMMARY OF THE INVENTION
The above objects and other objects, which will become apparent in
the description, are achieved by applying resin type material to
threaded articles, including fasteners such as nuts, bolts and
similar threaded articles and fasteners, and utilizing a method for
fastening such fasteners. In one aspect of the invention, a treated
form of a structural member having a coupled threaded article
adapted to exhibit a uniform torque-tension curve during coupling
of a mating fastener to the coupled threaded article is provided.
The uniform torque-tension curve characteristic exhibited by the
fastener results from application of a masking, insulating and/or
lubricating material to the threads of the threaded article. The
treated structural member and coupled threaded article are prepared
and the threaded article mating fastener are coupled in a process
which includes masking of the threads of the threaded article prior
to treating the structural member and prior to coupling the mating
fastener to the threaded article. The step of masking includes
supporting the threaded article for applying the coating material,
heating the threaded article to a temperature sufficient to enable
the coating material to adhere to the threads of the threaded
article, positioning a nozzle adjacent the threads of the threaded
article, discharging a gaseous jet containing the coating material
from the nozzle toward the threads of the threaded article and
depositing the coating material onto the heated threads of the
threaded article to form a substantially uniform masking,
insulating and/or lubricating coating on the threads of the
threaded article. The process also includes coupling the threaded
article to the structural member and treating the structural
member. The coated threads are thereby masked and/or insulated from
the treating step enabling the achievement of the uniform
torque-tension curve characteristic for reliably coupling the
associated threaded article to the mating fastener.
In another preferred embodiment of the invention, a fastener
resistant to the deposition of corrosion preventative material is
provided. The fastener includes a threaded portion adapted for
engagement with a mating fastener and an insulating coating deposit
on the threaded portion to form a substantially uniform layer. The
uniform layer provides an insulating barrier to the threads of the
fastener when about 500 to 600 volts of electrical potential is
applied across the uniform layer for at least two seconds.
One of the uses of the invention as described herein relates to the
automobile industry. However, those of ordinary skill in the art
will understand that this invention applies to other industries in
which parts or goods are assembled by threaded fasteners.
The problems stated above have been largely overcome by the present
invention which includes a threaded fastener having a head portion
at one end and a threaded shank associated with the head portion.
The threaded shank includes a tip portion at the end opposite the
head. At least a portion of the tip is coated with a lubricating
and/or masking material. The threaded fastener may include a screw,
bolt, or similar threaded article. Furthermore, the fastener may
include a self-threading screw, a self-drilling screw, or the like.
It has been determined that corrosion inhibitor build-up has been
substantially reduced by application of such material to the
threads of the fastening devices prior to coating with corrosion
inhibiting material.
Preferably, at least one thread of the threaded fastener is coated
substantially 360.degree. about its threaded shank with the
insulating, lubricating and/or masking material. Such a coating
reduces binding of the threaded fastener during installation and
typically improves the quality of the threaded fastener
installation. To prevent corrosion inhibitor build-up on the
threaded fastener during such processing, the threaded fastener is
preferably substantially completely coated with a lubricating or
masking material. This type of coating provides increased ease of
fastener installation after completion of the rust inhibitor
treatment.
A second embodiment of the fastener of the present invention
includes a fastening system having a male segment with a
substantially cylindrical threaded member which interlocks with the
threaded portion of a female segment. At least one thread of a male
or female segment includes a coating of an insulating, lubricating
and/or masking material. It may be desirable to coat all of the
threads of the male and/or female segment with an insulating,
lubricating and/or masking material depending on how the fastening
system is to be used.
The method of the present invention includes placing a first
article in fixed relation to a second article and placing a
threaded fastener having at least one thread coated with a
lubricating material through one of a plurality of preformed holes
in the first article. The fastener is then threaded into the second
article whereby the lubricating material reduces the drive torque
produced during the threading operation. This method is
particularly advantageous when the fastener is required to be
threaded through intermediate layers of a fibrous material placed
between the first and second articles. Such insulating material may
include insulating and/or carpeting material and the fastener may
include a self-drilling fastener to complete the threading
operation.
A second embodiment of the method of the present invention includes
a method of treating parts including a rust inhibiting material,
the parts, which include one or more fasteners thereon, have a
threaded portion. Such a method includes applying an insulating
and/or masking material to the threaded portion of the fasteners
and attaching the fasteners to the parts. The parts are then coated
with rust inhibiting material while the rust inhibiting material is
prevented from adhering to the threaded portion of the fasteners
due to the applied insulating and/or masking material. It may be
desirable to apply the insulating and/or masking material to a
heated fastener through the use of spraying techniques. This
provides a uniform coating of the insulating and/or masking
material as the material melts in the presence of heat.
Thus, a coated threaded fastener and apparatus for processing such
a fastener is provided which includes an insulating, lubricating
and/or masking coating on the threads of the fastener to reduce the
installation drive torque of the fastener and protect the fastener
from retaining unwanted materials during further processing. The
fastener/apparatus and method of using such fasteners of the
present invention provide cost savings and increased efficiency
over the fasteners and methods previously used.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and desired objects of
this invention, reference should be made to the following detailed
description taken in connection with the accompanying drawing,
wherein like reference characters refer to corresponding parts
throughout the several views of the preferred embodiments of the
invention in which:
FIG. 1 is a perspective view showing a device for the manufacture
of coated threaded articles and fasteners of the present
invention;
FIG. 2 is a sectional elevational view taken along the line II--II
of FIG. 1, showing details of the structure of FIG. 1;
FIG. 3 is an exploded perspective elevational view, taken on an
enlarged scale, showing elements forming an example of a supporting
platform in the structure of FIGS. 1 and 2;
FIG. 4 is a top plan view showing an example of a supporting
platform of the structure of FIGS. 1 and 2, taken on an enlarged
scale to show further details of the elements;
FIG. 5 is an elevational sectional view taken along the lines V--V
of FIG. 4; and also showing an adjacent vacuum hood;
FIG. 6 is a side plan view of the spray applicator for use in
processing the threaded articles and fasteners of the present
invention;
FIG. 7 is a side view of a spray applicator for use in processing
the threaded articles and fasteners of the present invention;
FIG. 8 is a side plan view of a third spray applicator for use in
processing the threaded articles and fasteners of the present
invention;
FIG. 9 is a perspective view of the spray applicator of FIG. 6;
FIG. 10 is a cross-sectional view of the spray applicator with a
gaseous jet of resin type material impacting the threads;
FIG. 11 is a top plan view of FIG. 10 showing the fan-like spread
of the stream of resin particles;
FIG. 12 is a cross-sectional view of another embodiment of the
apparatus used to process the threaded articles and fasteners of
the present invention. This embodiment is similar to the embodiment
of FIGS. 1 and 2, except that the powdered resin is applied at one
station only;
FIG. 13 is a top view of another embodiment of a spray applicator
used to process the threaded articles and fasteners of the present
invention in which the fastener is held stationary relative to the
spray applicator that is rotated about its axis;
FIG. 14 is a cross-sectional view of the applicator shown in FIG.
13, taken along the line XIV--XIV. In this view, the gear is shown
as disposed on the applicator so that it can be rotated in the
apparatus shown in FIG. 14a;
FIG. 14a is a cross-sectional view of one embodiment of an
apparatus for processing the threaded articles and fasteners of the
present invention that can use the spray applicator shown in FIG.
14. As mentioned above, in this embodiment, the spray applicator is
rotated while the threaded fasteners remain in a stationary
position relative to the applicator;
FIG. 14b is a perspective view of the spray applicator and gear
shown in FIG. 14;
FIG. 15 is a side elevational view, partially in cross-section of
an embodiment of an apparatus used to process the threaded articles
and fasteners of the present invention;
FIG. 16 is a side view of the embodiment shown in FIG. 15 with a
cutaway view of the spray applicator stage;
FIG. 17 is a combination schematic/apparatus diagram for an
embodiment of an apparatus and process used to process the threaded
articles and fasteners of the present invention providing control
over patch coverage longitudinally along the threaded article
and/or fastener;
FIG. 18A an enlarged view of the spray applicator or the nozzle
portion shown in FIG. 17;
FIG. 18B is a similar view to FIG. 18A with the spray applicator
and coupled conduit moved relative to the fastener in the view of
FIG. 18A;
FIG. 19 is a front elevational view illustrating a self-threading
screw of the present invention having coating material applied to
the tip portion of the shank;
FIG. 20 is a front elevational view illustrating a self-drilling
screw having coating material applied to the drill bit portion and
first thread of the screw;
FIG. 21 is a front elevational view illustrating a bolt having
coating material applied to the first thread;
FIG. 22 is a top elevational view of a triobul bolt having coating
material applied to the first thread;
FIG. 23 is a full perspective view of a nut having one coated
interior thread;
FIG. 24 is a front elevational view of threaded weld stud
illustrating coating material applied to all of the threads;
FIG. 25 a perspective view of a nut illustrating coating material
applied to all threads;
FIG. 26 is a top elevational view of a deformed all-metal nut
having coating material applied to all threads.
FIG. 27 is a bottom elevational view of the deformed all-metal nut
of FIG. 26.
FIG. 28 is a cross-sectional view of carpet positioned between a
door panel and interior door molding with a coated fastener
threaded therethrough; and
FIG. 29 is a cross-sectional view of carpet and sound insulation
positioned between door molding and a door panel with a
self-drilling screw threaded through all four items.
DESCRIPTION OF THE PREFERRED EMBODIMENT
While the present invention will be described particularly with
respect to applying various heat softenable resin particles,
fluorocarbon materials and Teflon (a registered trademark of DuPont
Corp.) to the threads of threaded articles, it is to be understood
that the- present invention can be utilized to apply a variety of
"resin type materials" to the threads of a fastener, including but
not limited to thermoplastic resins, thermoplastic resin compounds,
thermosetting resins such as epoxy resin and Teflon type compounds,
as well as other plastic and fluorocarbon type materials.
Referring to the drawings, and in particular to FIGS. 1 and 2 as
well as FIG. 12, there is shown apparatus for the manufacture of a
self-locking internally threaded article of the present invention.
While the invention contemplates a variety of threaded articles
and/or fasteners, including but not limited to nuts, bolts and
similar articles, the present invention will be described with
reference to a nut. The apparatus as illustrated generally includes
a rotatably mounted transport member in the form of a table 10
movable along a predetermined rotary path about its central axis,
in the direction shown by the arrows of FIG. 1.
As the table 10 is continuously rotated about a fixed housing 11, a
point on the table 10 will be seen to pass through a plurality of
stationary work areas referred to as stages of the operation for
the purposes of the present description. In the first stage of
operation loading chute 12, which is inclined downwardly toward the
surface of the table 10, is effective to deposit a nut N onto the
table 10. During the next stage a powdered material is applied
through a spray operation to the internal threaded surface of the
nut N. This stage is substantially enclosed by a vacuum hood 13,
the operation of which is explained in detail below.
In the embodiment of FIGS. 1, 2 and 12, a single depositing spray
stage is used, with the arcuate angular length of the application
varying according to the amount of deposit desired. While a single
powder application stage is shown herein, it will be appreciated
that multiple powder application stages may also be used, depending
on the type of deposit desired.
During the next stage an arm 14, connected to an inclined ramp 14a,
and having a cam surface disposed adjacent the upper surface of the
table 10 is effective to unload the nut N from the support
structure 24 and convey it in an opening in the support structure.
During a subsequent stage of operation, which substantially covers
that portion of the table 10 located between the unloading station
and the loading station, the means for applying resin type material
to the nut N are purged of residual material and are readied for
the next sequence of operation.
Referring to FIGS. 1 and 2, the stationary housing 11 is provided
with a funnel shaped hopper 15 which serves to receive the powdered
resin type material for application to the internal threads of the
nut N.
Referring to FIGS. 2 and 12, it will be noted that the table 10 is
provided with a table hub 16 which receives a ball-bearing member
17. The stationary housing 11 is provided at its upper portion with
a bearing surface 18 on which the table hub 16 and the ball-bearing
member 17 are received.
The external surface of the housing 11 further provides a second
bearing surface 20 on which is mounted a rotatable block 22. The
rotatable block 22 rests on a ball-bearing unit 23 disposed on the
upper surface of a support structure 24, which also supports the
stationary housing 11.
It will be noted from FIG. 2 that the cylindrical portion of the
stationary housing 11 on which the second bearing surface 20 is
formed, is substantially perpendicular to the support structure 24.
Therefore, the rotatable block 22 moves in a plane substantially
parallel to the surface of the support structure 24. However, the
cylindrical portion of the stationary housing 11 on which the
bearing surface 18 is formed is slightly canted with respect to the
surface of the support structure 24 providing for rotation of the
table 10 in a plane forming a slight angle with the surface of the
support structure 24 and the plane of rotation of the block 22.
The rotatable block 22 is provided with a ring gear 26 in meshing
engagement with a gear 28 connected to a drive motor. Extending
upwardly from the block 22 is a pin 29 which is slidably received
in a cylindrical bore 30 formed in the table 10. It will therefore
be evident from FIGS. 2 and 12, that operation of the motor to
drive the gear 28 causes rotation of the block 22 which in turn
drive the table 10 by virtue of the interconnected relationship
between the pin 29, the table 10 and the block 22. It should
further be evident that rotation of the block 22 and the table 10
causes the block 22 and the table 10 to move to various positions,
such as, a distance where the two members are in close relation to
one another and to a relative position where they are separated a
maximum distance apart in the manner shown.
Referring to FIGS. 1, 2, 5 and 12, the block 22 is shown to have
formed therein a plurality of circular cross-section apertures 32
each having an opening inwardly toward the stationary housing 11
and receiving a tube 33 at the opposite end, the tube 33 and the
aperture 32 forming in combination a conduit means. Attached to the
end of the tube 33 is a spray applicator 200 for controlling the
application of resin deposits and which is discussed in more detail
hereinafter.
Referring more particularly to FIGS. 6, 9 and 10, there is
illustrated generally at 200 the spray applicator constructed in
accordance with one form of the present invention. The applicator
200 comprises an elongated conduit portion or shaft 202 and a
nozzle portion 204. These nozzle and conduit portions have a
cylindrical passage 206 therein which is preferably concentric with
the shaft 202. In FIG. 6, the cylindrical passage (also the inner
diameter of the conduit or shaft 202), is shown by the dotted
lines. The passageway extends from a rear portion 208 of the
conduit 202 to the nozzle portion 204 where it curves slightly
upward at its entrance to the nozzle portion 204. The nozzle 204 is
provided with a slot or opening 210 which communicates with the
cylindrical passage 206. The nozzle portion 204 is preferably
cylindrical in configuration having an end portion which forms a
deflector surface 212. It has been discovered that varying the
width W of the slot 210, as best seen in FIG. 6, enables varying
the area of the resin deposit or patch applied. Control of the area
coated, and thus the number of threads coated, permits improved
masking of the internally threaded area, as well as improved
definition of the applied resin type material. Control in this
manner allows one to selectively avoid coating one or more of the
leading threads, therefore maintaining certain threads free of
resin particle deposit, providing improved torque performance and
enabling easy assembly of the fastener with a mating member. This
feature is illustrated in FIG. 10 where as shown the stream of
resin particles 214 is controlled so that the initial threads T1,
T2, T3 and T4, as well as the last thread T7 of fastener N are free
of resin particle deposit while threads T5 and T6 are coated.
It has been determined that the arcuate width of the slot opening
210 is important in the control and velocity of the resin particle
stream, as well as the arcuate coverage of the internal fastening
threads. Particularly, it has been found that when the
circumference of the slot opening is in the range of between about
one hundred ten degrees to about three hundred ten degrees, an
acceptable resin deposit or patch is applied. Spattering is further
minimized, while optimum velocity is also maintained, when the
circumference of the slot opening 210 is preferably in the range of
between about one hundred eighty degrees to about three hundred
degrees. The circumferential opening of the slot 210 is illustrated
by the arrows 216 of FIG. 9.
It has also been determined that the proportional relationship of
the diameter of the nozzle to the minor or inner diameter of the
fastener to be treated is also important in the deposition of the
resin particles. The diameter of the nozzle should be sixty to
eighty percent and preferably sixty-five to seventy-five percent of
the inner diameter of the fastener to be treated to provide
improved control and reduced spatter of the stream of resin
particles applied to the internal threads. Accordingly, variations
in the size of the diameter of the nozzle and its conduit portion
relative to the size of the inner diameter of the fasteners to be
treated are contemplated by this disclosure.
The optimum diameter of the nozzle for the above embodiment,
providing effective and efficient deposition of resin particles, as
well as improved patch definition to attain improved torque
performance, is approximately seventy percent of the inner, or
minor, diameter of the fastener. Nozzles that are sixty to eighty
percent of the inner diameter are within the operable range and
provide acceptable applied patches. Examples of such variations in
size of the nozzle diameter are illustrated in FIGS. 7 and 8. The
applicator 200 of FIG. 6 represents a relatively large size
diameter nozzle. The applicator 218 and the nozzle 220 of FIG. 7
represent generally an intermediate size configuration, and the
applicator 222 and nozzle 224 of FIG. 8 represent generally the
configuration of a form of the applicator 200.
The range of patch coverage for the arcuate internal threaded
surfaces of a fastener is also somewhat sensitive to the adjustable
depth of the slot or opening 210. For this particular embodiment it
has been determined that such a relationship may be expressed as a
percentage of the diameter of the nozzle portion 204 of the spray
guide applicator 200. Specifically, in order to obtain a desirable
patch of sprayed resin type material, the slot depth D is
maintained at between about thirty percent to about eighty-five
percent of the diameter of the nozzle position 204. Further, it is
preferred that the slot depth D be in the range of between about
forty-five percent to about seventy-five percent of the diameter of
the nozzle portion 204.
The cylindrical passageway 206 is constructed to be as large as
possible (as illustrated by the dotted lines in FIGS. 6-9
inclusive) consistent with maintaining strength of the walls of the
conduit portion 202. Larger passageways maximize the volume and
amount of resin type material which can be directed through the
conduit portion 202 while minimizing the amount of air or gas
pressure and the velocity of air required to move the resin type
material through the spray applicator 200. This feature improves
the definition of the resin deposition area by reducing spattering
caused in part by higher air pressures and velocities.
The spray applicators 200 of the illustrated form of the invention
are preferably formed of metals and alloys which readily dissipate
heat acquired by radiation or inadvertent contact with the heated
fasteners. Construction using these materials reduces the adherence
of resin type material on the walls of the applicator passageways
and helps eliminate clogging or restricted flow. Aluminum and
aluminum alloys are examples of suitable metals for forming the
spray applicators 200. Applicators made of steel, for example, are
generally less preferred since steel tends to hold the heat
transferred from the fasteners with the result that clogging and
restricted flow may occur. Accordingly, consistent with the
principles of the present invention, the spray applicators 200 are
maintained free from contact with the heated fasteners.
As shown in FIGS. 2, 3 and 5, the table 10 comprises an upper plate
35 and lower plate 34, the lower plate having a plurality of
circular openings 36 formed about its periphery and the upper plate
35 having a plurality of semi-circular walls 37 forming the outer
periphery adjacent the openings 36. The tube 33 is in communication
with each of the openings 36, and thus rotation of the table 10 and
block 22 causes the tubes 33 and the connected applicators 200 to
be moved upwardly through the openings 36 to a position shown at
the left of FIG. 2 and downwardly to a position shown at the right
of FIG. 2. This up and down movement is provided due to the angular
orientation of the plate and block during rotation of table 10 and
block 22, as described above.
As best shown in FIGS. 3-5, in one embodiment of an apparatus for
manufacturing the fasteners of the present invention, at each of
the openings 36 in the lower plate 34, a pinion gear 38 is
assembled by inserting a tubular flange 39 of the pinion gear 38
through the opening 36 from the underside of the plate 34. Locking
ring 40 is then press fit onto a flange 39 to attach the pinion
gear 38 to the plate 34. The locking ring 40 is of a thickness to
be received in a counter bore formed in the lower plate 34 such
that the upper surface of the ring is flush with the top surface of
the lower plate 34. Clearance between the opening 36 and the flange
39 is such that the pinion gear 38 is free to rotate when so
assembled.
Referring now to FIG. 1, taken together with FIGS. 4 and 5, at
selected arcuate segments of the path of circular rotation of the
table 10 and the block 22, one or more racks 41 are disposed such
that the teeth of the rack 41 are brought into meshing engagement
with the teeth of the pinion gear 38 during rotation of the table
and block combination. The rack 41 is mounted to the upper surface
of the stationary support structure 24 as best shown in FIGS. 2 to
5. While the means for contacting the pinion gear 38 is shown
herein as the stationary rack 41, it should be evident that such
means could be a variety of interengaging structures. Such
structures include, but are not limited to circular ring gears
having internal teeth aligned to mesh with the pinion gear 38 at
desired locations, or portions of such a gear employed in a similar
fashion as the described racks.
In accordance with one form of the invention, means may be provided
at the spraying stage, beneath the hood 13, to contact the outer
flange face of the periphery of the nut N, while the nut N is being
processed at that stage. As shown in FIG. 1, a silicone belt 42 is
threaded over a plurality of pins 43 to form a substantially
arcuate belt surface, conforming to the periphery of the flange on
the nuts N, as they are rotated.
In operation the illustrated embodiment of FIGS. 1 and 2 employs
the principles taught in U.S. Pat. Nos. 3,995,074, 4,054,688 and
4,100,882 in dispensing material from the funnel 15 to the exit
point from the outer end of each of the tubes 33. Briefly stated,
at the hopper 15 are provided preferred resin type materials
including, but not limited to Teflon, Teflon compounds, resin
powders, thermosetting resins, thermoplastics, nylon powders, resin
powders and similar sprayable powders. The powders are forced
through the tubes 33 by fluid pressure generated by an air pump
(not shown), the air pressure being introduced into the circular
bore 45 in the housing 11. In the illustrated embodiment it is
desired to provide continuous deposition of resin type material on
the fastener throughout an arcuate segment of rotation of the table
10. Accordingly, as shown in FIG. 2, the table 10 includes an
arcuate bore 48 provided in the housing 11 extending over an
arcuate segment of rotation of the table 10 through the housing
from the circular bore 45 to the circular aperture 32 when aligned
with the arcuate bore 48.
Referring now to FIG. 1, a sequence of operational steps will be
described in which it is desired to provide a locking patch over
three hundred sixty degrees of a portion of the internal threads of
the fastener element N. In practicing the teachings of the
illustrated embodiment, fasteners N are fed from a vibrator device
or similar orienting and feeding device (not shown) into a chute 50
which is surrounded by heating means, such as, a heating coil 51.
The fastener N is raised to a temperature sufficient to cause a
powdered resin type material to adhere to the threaded surface of
the fastener when contacted thereby and fused by heat from the
surface to form a continuous patch. As each fastener N approaches
the table 10, the fastener will be deposited in registry with the
semi-circular wall 37 of the plate 35 (see FIGS. 2 and 3).
In the described typical cycle operation, a plurality of the
fasteners N are contained on a vibratory feeder or other device
(not shown) which is effective to feed the fasteners into the chute
50 where they are passed through the heating coil 51 and raised to
a temperature sufficient to cause a resin type material powder to
adhere to the threaded surfaces of the fasteners.
Each fastener N is in turn located in a position as shown in FIGS.
4 and 5 wherein the flange of the fastener N is disposed on the
surface of the table 10 adjacent the semi-circular wall 37,
supported partially by the tubular flange 39 of the pinion gear 38
forming a rotatable platform for the fastener N. The fastener N is
then passed into an area along the circular path of the table 10
wherein the circular cross-section aperture of the tube 33 is open
to the arcuate bore 48, providing the flow of the resin type
material through the bore and tube 33 and onto the threads of the
flanged nut N.
In the instances where a patch is to be applied about the complete
circumference of a portion of the internal threads of the nut N,
(i.e. a three hundred sixty degree patch is desired), rotation of
either the spray tubes and/or the nut to be processed can be
accomplished in the embodiments shown in FIGS. 1, 4, 5, 13, 14 and
14a in order to obtain a satisfactory applied patch. In other
instances, rotation of the nuts or spray tubes is not desired and
resin is deposited on a portion of the three hundred sixty degree
path of the internal threads, as described in detail above.
Accordingly, in one embodiment, rotation of the nut is accomplished
as the nut N approaches the point where the aperture 32 of the tube
33 is positioned for flow of resin type material. Specifically, the
pinion gear 38, on which the fastener N is resting, is brought into
meshing engagement with the rack 41. The pinion gear 38 is then
caused to turn, thereby rotating the fastener N during deposit of
the resin type material and applying a three hundred sixty degrees
patch about a desired portion of the threads.
In an alternate embodiment shown in FIG. 12, the structure and
operation of the apparatus is similar to the embodiment shown in
FIGS. 1 and 2. The apparatus is disposed upon a spacer 301 which
supports a post 304. A gear 310 that is carried upon a horizontal
ring tube 311 which rides upon a ball bearing 303 about a post 304.
A horizontal tube 312 is fitted in an internal conduit 322 formed
in the ring tube 311. One end of an elbow 313, generally formed of
a plastic tubing material, is fitted on the end of the horizontal
tube 312. The other end of the elbow 313 is fitted onto the spray
applicator 315. The spray applicator 315 is rigidly disposed in a
tube holder 314 that is affixed to the ring tube 311. Resin type
particles that are to be applied to the threaded fasteners flow
through a powder feed tube 321 that is canted at an oblique angle
to the apparatus. As the powder emerges from the feed tube 321, the
particles strike the generally conically shaped disperser 323 from
whence it flows through a conduit 324 formed in the post 304. As
the internal conduit 322 indexes in front of the conduit 324,
powder will flow into it and thence into the tube 311 and finally
into the spray nozzle portion 315. As the powder emerges from the
mouth 315a of the nozzle portion 315, it impinges upon the nut N
and deposits upon the threads as described previously.
In another embodiment as illustrated in FIGS. 13, 14 and 14b, a
three hundred sixty degree patch application can be achieved by
rotation of a spray guide applicator 228 through which the powdered
material is sprayed. In this regard the spray applicator 228 has a
nozzle opening 230 and a coupled conduit portion or shaft 232, and
further included is a pinion gear 234. The pinion gear 234 is press
fit over the end, opposite the nozzle opening 230 and is positioned
on the shaft 232 so as to abut a shoulder 236 on the shaft 232.
As can be seen in FIG. 14a, the pinion gear 234 is rotated as it
approaches the point at which an aperture 250 of a tube 251 is
positioned for flow of resin type material, so as to apply a three
hundred sixty degree patch or ring to a portion of the internal
threads of the fastener N. This operation is similar to that
described above in reference to FIGS. 4 and 5. Specifically, the
pinion gear 234 is brought into meshing engagement with a rack 237
which causes the pinion gear 234 and an attached spray guide
applicator 238 to rotate within the fastener N. The rack 237
includes a pawl and spring (not shown) which together act as an
expandable guide path for accepting the pinion gear 234 and
preventing backward motion. Construction in this manner helps to
alleviate path alignment problems which could be caused by
misalignment of the pinion gear 234 and the rack 237.
This spraying operation described above takes place for at least
one complete rotation of the spray applicator 228 over a
predetermined arcuate path of travel of table 211 in FIG. 14a so
that a three hundred sixty patch or ring of minimum acceptable
thickness is applied to a portion of the internal threads of
fastener N. It should be understood that powder flow can be
adjusted during the spraying operation to adjust the amount of the
resin type material deposited on the fastener during that time
period. Such adjustment of powder flow accordingly determines the
thickness of the patch which will be applied to the fastener
threads.
As previously described with reference to FIG. 2, the arcuate bore
48 is designed and fabricated to include that arcuate portion of
the table rotation adequate to cover the desired portion of the
internal threads on which the patch is to be deposited, taking into
account the rotation of each fastener N or the spray applicator 200
relative to the rotation of the table 10. As an example, if its is
desired to deposit a patch covering the full three hundred sixty
degrees of a portion of the internal fastener threads, the arcuate
bore 48 will be disposed over an arc through which the table 10
travels during at least one rotation of the fastener N or rotation
of the spray applicator 200 through three hundred sixty
degrees.
While covering the full three hundred sixty degrees of a portion of
the internal fastener threads is preferred in certain instances, a
fastener satisfactory for selected purposes, such as acceptable
torque performance and patch definition, can be accomplished by
covering less than three hundred sixty degrees of the fastener
threads. It has been determined, for example, that satisfactory
torque performance can be obtained from an internally threaded
fastener being used one time by having thread coverage in the range
of between about ninety degrees to three hundred sixty degrees.
More preferably, for internal arcuate thread coverage a range of
from about between one hundred ten degrees to about two hundred
seventy degrees is often best.
In the situation where the fastener will be subject to reuse, it
has been determined that internal arcuate thread coverage in the
range of between about one hundred thirty degrees to three hundred
sixty degrees provides satisfactory torque performance. A more
preferred range for reusable fasteners is between about one hundred
eighty degrees to two hundred seventy degrees of internal arcuate
thread coverage.
In another embodiment shown in FIG. 17, the patch of resin type
material is applied to the threads of a threaded article 346 having
at least one open end and typically open at both ends, such as for
nuts. The apparatus includes means for supporting the threaded
article 346, such as, for example, a simple mounting shelf 350 as
shown in FIG. 17. Heating means is provided to heat the threaded
article 346 to the temperature needed to cause adherence of the
resin type material to the threads. The temperature of the threaded
article 346 is sensed in a known manner by an optical pyrometer 353
and coupled fiber optic sensor 349. In the illustrated embodiment
the heating means is an RF induction heating coil 352. A nozzle
portion 354 shown in FIG. 18 is also provided for spraying the
resin type material onto the threads. The sprayed type material
which does not adhere to the threaded article 346 is removed by
suction means, such as vacuum nozzle 355 shown in phantom in FIG.
17. Various means can be used for generating the gaseous jet
containing the resin type material. A stream of gas for producing
the gaseous jet is provided by an air input 349 and coupled flow
meter 351 generating the desired gaseous jet which combines with
the resin type material. Additional details of the source and
control of resin type material will be discussed hereinafter.
In FIG. 18 are shown details of the configuration of the nozzle
portion 343. A cylindrical conduit 356 and an end plate 358 of the
nozzle portion 354 cause the gaseous jet containing the resin type
material to pass along path P through the conduit 356 disposed
between the open ends (or the two open ends of a nut) of the
threaded article, and path P is substantially parallel to the
longitudinal axis of the threaded article 346. The gaseous jet then
continues along the pat P until striking the end plate 358. The
gaseous jet is diverted along path D toward the threads of the
internally threaded article 346. The directions of flow of the
gaseous jet at nozzle opening 360 after diversion along path D are
substantially perpendicular to and radially extending about the
longitudinal center line of the threaded article 346. In a
preferred embodiment that gaseous jet is diverted along path D,
forming a substantially circular thin layer at the nozzle opening
360. The longitudinal extent of the layer is controllable by
varying the size of the nozzle opening 360, such as by using a set
of different fixed opening sized of the nozzle 354 or by having
continuous variability of the nozzle opening 360 through
displacement of the end plate 358 relative to the terminal end of
the conduit 356. Means for accomplishing this relative displacement
can include, for example, a threaded drive shaft 362 coupled to the
end plate 358, a hydraulically driven form of the drive shaft 362
or other equivalent means for relative displacement of the conduit
356 and the end plate 358. Additional control of the shape of the
gaseous jet emerging from the nozzle opening 360 includes changing
the angle of radial inclination of the end plate 358. In a
preferred form of the invention this angle of inclination, alpha,
shown in FIG. 18B, is approximately two degrees in order to avoid
overspray onto undesired portions, such as the face portions at
either end of nuts.
Relating to the above mentioned adjustability of the nozzle opening
360, there is included means for selectively moving and controlling
the spatial position of the nozzle portion or spray applicator 354
illustrated in detail in FIG. 18. At the beginning of an
operational duty cycle of forming a patch, the internally threaded
article 346 is first positioned to establish the terminal end of
the nozzle portion 354 at the position shown in FIG. 18A. The
apparatus is actuated by an operator 364 or by an automatic control
365 (shown schematically) applying electrical power to a solenoid
operated directional valve 366. The direction valve 366
accomplishes movement of the nozzle portion 364 into the opening of
the internally threaded article 346 by air input from the
directional valve 366 to an air drive cylinder 368 coupled to the
applicator portion 364. Activation of the apparatus and/or movement
of the drive cylinder 368 is also coupled through a relay 370 to a
powder dispenser 372 and associated electric vibrator 373 and also
to an air spray unit conduit 374. This coupling of components
enables delivery of powdered resin type material from the powder
dispenser 372 and generation by the air spray unit 374 of an air
stream. The powder and air stream are then combined in the conduit
356 to form a gaseous jet containing the resin type material. As
discussed hereinbefore, the gaseous jet is output along the path P
shown in FIG. 18B, striking the end plate 358, and the powdered
resin type material in the gaseous jet is diverted along path D to
the threads of the threaded article 346 to form the patch
thereon.
The rate and direction of travel of the nozzle portion 354 along
the longitudinal axis of the threaded article 346 can be controlled
by the pressure level, as regulated by flow control valve 375 for
forward motion and flow control value 376 for rearward motion. To
vary the length of travel for the nozzle portion 354, microswitches
378 and 380 are used in the illustrated embodiment to determine the
reverse motion and stop positions, respectively, for the air drive
cylinder 368 coupled to the nozzle portion 354. At the end of the
chosen duty cycle the microswitches 378 and 380 also can deactivate
powder flow from the powder dispenser 372 and flow of the gaseous
jet. The end of the duty cycle can be, for example, at the end of
the forward stroke position of the drive cylinder 368 or can be at
the return to the starting position, or multiples of the selectable
positional ranges.
Other means for controlling start, reverse motion and stop
positions for the drive cylinder 368 can be used, such as, for
example, a plurality of microswitches or a rheostat positionally
coupled to the location of the drive cylinder 368 to enable
carrying out a voltage controlled duty cycle for the nozzle portion
354. Moreover, such means can be coupled to the flow control valves
374 and 376, enabling the velocity of the drive cylinder 368 to be
controlled throughout the range of the duty cycle. This feature
allows careful control of relative amounts of resin type material
deposited along the length of the threads encompassed by the duty
cycle.
A particularly advantageous use of the embodiment of FIGS. 17 and
18 is the application of a Teflon type patch, preferably covering
all the threads of the threaded article 346 with a masking,
lubricating and/or insulating covering. A thermoplastic type
Teflon, such as Teflon-P powders (see DuPont Technical Information
Pamphlet TI-13-84, incorporated by reference herein) is sprayable
onto the heated threads of a threaded article forming a Teflon
covering which masks, insulates and/or lubricates the threads of a
threaded article. The threaded article 346 undergoes the
aforementioned processing steps with the gaseous jet containing the
Teflon-P powders sprayed from the nozzle 354 onto the threads. The
threaded article 346 is raised to a temperature of about
700.degree. F. by an RF generator, and a substantially uniform
Teflon covering is achieved with a layer thickness being at least
about 25 to 50 microns. In an average case the thickness at the
root and crest of the threads was about 20 to 30 microns. In
preparing the Teflon coatings it was found to be unnecessary to
perform the recommended DuPont post preparation heat treatment (see
DuPont Pamphlet TI-13-84 indicated above). A finished substantially
uniform, pinhole free Teflon covering which masked, lubricated
and/or insulated the threads of the article was obtained in most
instances directly from the spray application process. In some
cases, such as for small nuts which cool rapidly, it is desirable
to perform a post layer formation step of pulse heating at about
700.degree. F. for a few seconds to achieve better Teflon coating
integrity and performance characteristics. It should be understood
that any short heat treatment based on known methods and apparatus
can be used to perform this post deposition heat treatment.
The current commercial grade DuPont Teflon-P powders have an
average size of about thirty-seven microns and a size range from
one to one hundred microns. Different size distribution Teflon-P
powders are also available from DuPont Corp. Although Teflon-P
powder from DuPont Corporation is preferably used for preparing the
desired Teflon coatings, other similar formulations of powders
having substantially the same chemical makeup and particle size
distribution can be used with equal effectiveness.
Fasteners prepared in accordance with the above described procedure
have found particularly significant use in joining treated
structural members to other structures. Recent progress been made
in improving the corrosion resistance of automobile bodies using
formulations for treatment of steel structural members, such as,
for example the PPG Corporation Uniprime coating product (Uniprime
is a trademark of PPG Corporation). When treating an automobile
structural member using Uniprime, the cured material forms a
protective layer over the underlying metal. When a fastener coupled
to the structural member is engaged with its mating fastener and
the threads of the coupled fastener or the mating fastener are
coated with Uniprime, it is virtually impossible to obtain the
proper fastener tension in the standard assembling operation
involving the torque-tension measurement on the fastener
coupling.
A proper torque-tension curve or test insures achievement of a
prescribed range of bolt or fastener tension for fastener coupling.
However, the presence of the Uniprime layer can result in many
problems, such as stalling of the bolt driver and result in unknown
bolt tension. The Uniprime layer can also undergo cracking and
separation, causing anomalous torque-tension results. A mask layer
can be placed over the threads to prevent contamination from
Uniprime, as well as to prevent other interfering, or extrinsic,
contaminants from being deposited on, or remaining on the threads
by enabling ready removal from the threads. A properly prepared
mask layer which masks, insulates and/or lubricates the threads of
the fastener can thereby insure a reliable torque-tension curve
result for fastener couplings. The Teflon coating, however, should
be reliably and uniformly placed over all the threads, but
preferably not on other fastener surfaces which are often desirably
coated with Uniprime or other corrosion preventative materials or
with finish coatings.
Other methods have been tried and have been unsuccessful, both for
internally threaded articles and externally threaded articles. Due
to the low viscosity, liquid application of the Teflon covering to
internal threads causes highly irregular coverage, and for external
threads on bolts only electrostatically charged liquids have
heretofore found success. The Teflon covering must be uniform in
thickness and should be substantially free of pinholes in order to
avoid deposition of on the threads small quantities of Uniprime, or
deposition on the threads of other extrinsic contaminants which
cannot be readily removed from the threads.
Using the above described powder spraying techniques and apparatus,
the desired substantially uniform Teflon type covering can be
provided to mask, lubricate and/or insulate the threads of a
fastener, enabling highly reliable torque-tension tests or curves
to be obtained after installation of the fastener and further
processing of the structural member on which the fastener is
installed. The ability to carry out such reliable tests achieves a
high yield of fastener coupling with the desired strengths and much
higher commercial production efficiency. Various types of fasteners
can be coupled to a structural member and can benefit from the
invention. These fastener types can include, for example, nuts,
studs, bolts, internally threaded wells and an internally and
externally threaded bolt.
In general the preferred form of the apparatus for producing
fasteners of the present invention includes vacuum means, such as a
hood shown in FIG. 1, for producing a suction force or a negative
pressure at the vacuum nozzle 355 in the embodiment of FIG. 17. The
vacuum means functions in a manner similar to those systems
disclosed in the aforementioned prior art, serving to remove excess
material during the application of a patch. One main requirement of
such vacuum producing means is to provide a negative pressure or
suction area adjacent the upper opening of internally threaded
fasteners for drawing air in through the opening at the lower end
to reduce deposition of resin type materials which have passed
through the threaded portion of the fasteners.
FIGS. 15 and 16 illustrate another embodiment of the apparatus used
to produce fasteners of the present invention. Specifically, a
single unit apparatus is shown for preparing nuts one at a time and
is illustrated generally at 400, and includes a chamber 402 into
which air is directed at one end through inlet 404. Chamber 402
includes a passageway 406 extending substantially across its
length. A powder funnel 408 is positioned proximate t the inlet 404
and in communication with the passageway 406 of the chamber 402.
The chamber 402 also includes an air exit port 410 at its end
opposite that of the inlet 404 to which one end of the conduit 412
is removably attached through a mounting structure, such as
threaded sleeve 414. The opposite end of the conduit 412 is
attached to any applicator G of the spray applicators described
hereinbefore. Specifically, a spray applicator similar to the spray
applicator 218 of FIG. 7 is illustrated; however, any size
applicator G can be substituted depending on the size of the nut N
being processed.
The spray applicator G is directed through a nut support 416 on
which a fastener or nut N is placed for processing. A vacuum hood
420 is typically placed generally over nut N and in association
with a vacuum source (not shown), completing the air flow path
through the apparatus thereby collecting powder which is not
deposited on the internal threaded surfaces of the nut.
In operation the powder funnel 408 is provided with a source of
resin type material powder to be applied to the nut N. The powder
is entrained in the air stream or gaseous jet provided at the inlet
404 and is carried through the passageway 406, the exit port 410
and the conduit 412 to arrive at the spray applicator G. The air
entrained powder is then directed onto a predetermined portion of
the arcuate internal threaded surfaces of the nut N for application
thereto. Any powder not applied to the nut N is directed out of the
internal area of the nut N by the vacuum hood 420. The resin patch
is applied to the nuts N in a more consistent, controllable and
cost efficient manner.
Another form of the present invention will be described in relation
to a particular type of fastener, namely a stud which includes a
head portion, a shank portion and a plurality of projections
depending downwardly from the head portion parallel to the central
axis of the shank portion. However, it is to be understood that the
present invention contemplates coating a variety of fasteners,
including, but not limited to, screws, bolts, studs and similar
externally threaded articles. Furthermore, it may be appreciated by
those skilled in the art that the present invention may have
advantages and may be used to provide a coating on a wide variety
of internally threaded articles including, but not limited to,
nuts, including deformed all-metal nuts, collars and the like.
The present method and described apparatus may also be used to
apply a variety of coatings to fasteners. Such coatings include,
but are not limited to, non-conductive coatings, masking coatings,
insulating coatings, lubricating coatings, a combination of such
coatings as well as similar types of coatings. Furthermore, such
coating materials may include, but are not limited to,
thermoplastic or thermosetting materials. Specifically, such
coatings may include, but are not limited to nylon, acrylic, as
well as fluorocarbon and polyethylene based materials. An example
of such a material is manufactured by DuPont Corporation and is
distributed under the trademark Teflon-P.
The coating material is preferably applied by spraying a powder
onto the threaded fastener, however, a variety of application
methods may be utilized. Such methods include gravity application,
splatter application and the like.
FIG. 19 depicts a screw 510 including a head 511, a shank 512, and
the tip 513. Tip 513 is tapered to a point. The tip 513 is covered
with a coating material 514.
As can be seen, at least one thread is coated with the lubricating,
insulating or masking material. To coat more than one thread,
however, may be uneconomical in certain applications. As a fastener
is drilled or threaded, the coating material on the drive flank of
the thread may be severed and scraped off by friction. The coating
material assumes a granular form and may act to further lubricate
either or both of the drilling and threading operations.
Another illustration of the invention as it relates to providing a
fastener at least partially coated with a lubricating material
appears in FIG. 20. A self-drilling screw 515 has a head 516, shank
517 and a tip 518. Tip 518 is configured like a drill bit. The
lubricating material 519 coats the tip 518 and the first thread of
shank 517. This has proved advantageous in reducing drive torque
when fastener 515 is used to drill a hole and the same fastener is
then subsequently threaded into the hole it first drills. Drive
torque is reduced in both the drilling and threading
operations.
Various tests have been carried out in developing the present
invention. For example, a comparison was made under identical
circumstances between screws with an applied teflon coating and
those without. The first test involved #8-18.times.3/4 inch long
pan head self-drilling screws. For each screw tested, a 1/8 inch
diameter starter hole was pre-drilled in low carbon steel 18 gauge
sheet metal. A torque wrench was used to turn the fastener for five
revolutions into the sheet metal. The maximum torque, in inch/lbs.,
was noted for each self-drilling screw. Twelve zinc-plated,
self-drilling screws without teflon were used, as were twelve
self-drilling screws that were coated completely from the tip of
the drill point to half way up the thread length of the shank. The
average reading for the screws without teflon was 34 percent
higher, 17.6 in./lbs.
Similar results occurred when the same comparison was made with
#6.times.1 inch long pan head self-tapping screws. 0.104 inch
diameter starter holes were pre-drilled in the sheet metal. The
twelve screws that were teflon coated for half of their thread
length used an average of 20.6 in./lbs. as the maximum torque. The
screws without teflon, but only their original dry phosphorous
plating, showed a 16 percent increase in the maximum torque, to
23.9 in./lbs.
Besides a unitary piece, such as a screw, this invention also
reduces drive torque in a nut and bolt combination. FIG. 21 depicts
an ordinary hex-head bolt 520 which includes a head 521 and a shank
522. A first thread 523 of shank 522 is illustrated having a
lubricating coating applied thereon. Other bolts can be treated in
a similar manner. For example, FIG. 22 shows a sectional view of a
trilocular bolt 525 that is used to ensure that a nut and bolt
remained fastened. The shank 526 has three rounded lobes 527. The
first thread of the shank is coated with a lubricating material
528. FIG. 23 presents an equally successful alternative to coating
the threads of bolts. In particular, a nut 530 with threads 531 has
its first thread coated with a lubricating material.
Application of a lubricating material is also effective in reducing
drive torque when applied to bolts, in the form of weld studs, and
nuts that are attached to, e.g., automobile parts that must be
fastened together. An equally important embodiment of this
invention is having the threads of the fasteners completely coated
with a lubricating material, which then acts as a masking or
insulating material in preventing the build-up of corrosion
inhibitors which include Uniprime and the like.
For example, in FIG. 24 a threaded weld stud 534 is composed of a
head 536 and a shank 537. The shank of the weld stud is entirely
coated with a masking material 538. When the stud is welded to an
automobile part that is later coated with a corrosion inhibiting
material, the material does not adhere to the threads.
Consequently, when that threaded stud is used in a fastening
operation on an automobile assembly line, no difficulty is
encountered in fastening, so production continues unimpeded.
FIG. 25 demonstrates the same principle as it applies to a nut,
rather than a threaded weld stud. A nut 539 has its threads 540
completely coated with a masking material 541. When the nut is
welded to an automobile and subsequently coated with corrosion
inhibiting material, the amount of residual corrosion inhibitor
which may remain does not impede the fastening process. The same
masking technique can be used when a part simply has a threaded
hole drilled through it, rather than having a fastener
attached.
FIGS. 26 and 27 illustrate another embodiment of the present
invention. A deformed all-metal nut 542 is shown which includes
internal threads 543 which are completely coated with masking
material 544. Deformed all-metal nut 542 also includes a top
surface 545 depicted in FIG. 26 and a bottom surface 546 depicted
in FIG. 27. As can be seen, bottom surface 546 includes a deformed
thread, typically the outermost one or two threads of the nut. This
type of coating is a great improvement over the cadmium wax coating
previously used in that it eliminates the inherent dangers,
including personal and environmental hazards, associated with using
a radioactive coating.
The self-drilling screws with such a lubricating and/or masking
material have also solved what previously had been a particularly
vexing problem, particularly to the automobile industry. Fibrous
material cannot be cut and aligned with the precision of machined
parts. When an assembly line worker installs a piece of carpet on
an interior door panel, there are no holes in the carpet. The
carpet is aligned by hand and molding with pre-formed holes is held
over the carpet. A self-drilling screw is placed through the hole
in the molding and is then drilled through the carpet and threaded
into the interior door panel. In the past, self-drilling screws
would bind in the fibrous carpet. The lubricating and/or masking
coating on the drill tip and/or at least a portion of the threads
of the self-drilling fastener, substantially reduces and may
prevent binding during installation. In addition, the coating
material on the threads reduces the drive torque necessary to
fasten the screw once it has pierced through the fibrous material
and drilled into the door panel.
FIG. 28 depicts a sectional view of a self-drilling fastener
installed through fibrous material such as carpet. Carpet 550 is
placed against the interior side of a car door panel 552. Molding
554, with a performed hole 555, is placed against carpet 550. When
carpet 550 and molding 554 are properly aligned during the assembly
process, a coated self-drilling fastener is drilled through the
carpet and threaded into the car door panel 552. FIG. 29 shows the
completed process wherein the head 560 of a self-drilling fastener
562 sets in a recess of molding 554 and fastener 562 passes into
door panel 552. In addition, FIG. 29 shows a layer of sound
insulation 565 placed between carpet 550 and door panel 552. Thus,
to accomplish the assembly depicted in FIG. 29, the self-drilling
fastener must have passed through two consecutive layers of fibrous
material.
Accordingly, improved coated fasteners or threaded articles and an
improved method for using such articles is provided. The threaded
articles include a resin type material applied to a predetermined
area of the threads of a threaded article leading to improved
performance characteristics, as well as improved patch definition.
In particular, a Teflon patch can be applied to the threads of
threaded articles achieving a substantially uniform covering of the
threads providing a masking, lubricating and/or insulating covering
enabling highly reliable torque tension tests to be performed on
fasteners coupling corrosion treated structural members, such as
are present in automobiles.
While the invention has been described with respect to preferred
embodiments, it will be apparent to those skilled in the art that
changes and modifications may be made without departing from the
scope of the present invention in its broader aspects. Accordingly,
it is intended that all matter contained in the above description,
or shown in the accompanying drawing shall be interpreted in an
illustrative and not in a limiting sense.
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